Short wave radioreceiver



Jan. 1, 1935. J. G. STREIFFERT ET AL 1,986,081

SHORT WAVE RADIORECEIVER Filed Dec. 31, 1931 will readily be understood. The leads shown on Figure 1 extending from the grid and plate to the condenser are connected to fastening members 34 and 35 securing the plates 36 and 37 which make up the condenser 15. As shown in Figure 2, the plates 36 and 3'I-extend toward each other from opposite sides of the base 32 and terminate in enlarged portions which are approximately parallel. The distance between these plates and the base is exaggerated'inFi'gure2'for clear'ness}. a. I

The plate 36 which is remote from the tube 10 is resilient and tends to spring away from the plate 3'7. An adjusting screw 3 8 .,is supported by posts 39 and 40 extends through aligned bores; formed? in :saidposts. The bore in post 40 is threaded to receive, the threaded portion of screw 38. ,v It is evident that rotation of the screw "40" will vary the distance between the plates 36 and 37;gand wills thereby vary the capacity of the condenser 15. The peculiar construction :of' the condenser 15 allows it to be positioned-very close to" tube 10 andthus theleads: from the grid and-plate to said condenser areof-minimum length. Also the inductances 16 and 17- may-be directly-connected -to '-the-' plates o'f the condenser without the -use' of intermediate leads.- "The condenser 18 is of-greater-capacity than condenser 15-and is constructed-similarly thereto, having twoplates 41 and 42 secured to"-the=.base 32 at :the end thereof remote from the tube lO-bymeans of. screws 43 which also'retainpillars 33 in position.

As shown, the plates of condenser-:18 are directly connected: to theinductanceslfiand 1'7, eliminating 'intermediate leads between the inductances and the condenser. adjusted by 'means-off an adjusting screw 44 mounted in post 40. 111 the'above described construction'inductances 16 and 17 f-a'resecured in spaced parallel relation" on the upper surface of base 32. x i-11. 1 1' Conder'iser 15fis usedfor the actual tuning'of the circuit toa signal of a given frequency and condenser '18 is used to 'determine the "wave band upon which it is desired -'to operate the receiver. That is, a-certainxsetting of condenser 18 would suffice-"t'o' receive signals overa band -of "fre-' quencies or wave "lengthsfor example, say i 1.9

meters to 2.1 meters and condenser 15-would be used to select the desired frequency within-this band; If it-is desired' to provide a receiver operating overra restricted band of-wavelengths such as mentioned above, it is understood that al fixed condenser of -the predetermined capacity necessary can be'locked in the position of the variable condenser 18" andthe adjusting screw 44 eliminated; I

It will thusbe seen f that .I have provided a complete tuning circuit for ultra-highxfrequencies, the parts 0f which combiner to-form a structure which ismecha'nically symmetrical and which practicallyeliminates the use of leads be tween the -variou's parts thereof ,with"their,undesirable distributed inductance and capacitance. The pillars 33 which 'supporttheright end of thebase32 :as viewed-in Figure'2, may also serve as supports for the radio frequency chokes 19-and 26which may be connectedtQ the screws 43 below the base32 and temnnals-(not-shown) may be positioned at the lower end of pillars-3'3 for connecting the 'chokes to therem'ain'der of the circuit asindicatedin Figure1-. J w

In operationthe condenser 18 1s adjusted such that the tuningcircuit correspon'dsj-tothe'desiredwave "band ian'd condenser 15 is adjusted mounted upon'tlie base 32 'and Condenser l8ma'y: be

lation will be set up in the tuning circuit, comprising the inductances 16 and 17, the condensers 15 and 18, and the grid-plate capacity of the tube. The potential of the grid will vary at the frequency of thesignalzand as avfunction of the amplitude thereof and will.:control the current in the plate circuit, as will be understood.

Since inductance 17 in the plate circuit forms part of the oscillating circuit and the plate circuit is"capacitively coupled to the grid circuit ,by. the condensers 15 and 18, variations in the platelpotential and current will increase the electrical oscillation of the tuning circuit, thus "increasing the variation of the grid potential and the amplitude of the plate current.

The ultra-high frequency current is confined to the tuning circuit and the radio frequency chokes 19and 26 are effective to prevent the flow ofsuch high frequency current in the remainder of the circuit. 7 v a Since the plate current is not a straight line functionof the grid potential, a variation in the amplitude-of the impressed signal at a lower frequency will produce asa component of the plate current, an'alternating current of the lower frequency. This alternating current will flow through inductance '25, and since this inductance is inductively coupled to inductance 23, the-potential of the gridwill also bevaried at the lower-frequency, thusincreasing the amplitude of the lower frequency component of the plate current.- The coupling between' inductances' 23 and 25 is variable to provide a control over this increase in the amplitude of thelower frequency current. g 7 As shown in Figure 1, this current will alsoflow. through a load connected to the output terminals 2'7 and 30, which load may be an-indicating -device-such as an annunciator, relay or meter, or a second vacuum tube circuitemployed as a linear; amplifier. l I The abovei description or. theoperation'of the device is merely for the purpose "of explanation, and'it is =understoodtha't applicants are not to be-limited to any particular theory of operation. By way of example the values of the capacitance and resistance of certain of the elements Iwhich may be used in the device are given The foregoing description illustrative only of the invention andis not to be construed in alimiting sense, as the "scope of the] invention is defined by the appendedclaims. I-Iaving thus described our invention, what we said condenser plates, a second condenser mounted upon and arranged transversely of said base and having its terminals directly connected to the ends of the inductances remote from the first mentioned condenser, said base being mounted upon pillars, radio frequency chokes mounted upon said pillars and having a terminal of each connected to the terminals of said second condenser.

3. In a radiocircuit for ultra high frequencies, a vacuum tube having a grid, plate and cathode,

a grid circuit connected to said gridv and said cathode, a plate circuit connected to said plate and said cathode, and a tuning circuit for said ultra high frequencies comprising a series inductance in said grid circuit adjacent said tube, a series inductance in said plate circuit adjacent said tube, said grid and plate circuits being bridged adjacent said tube by a condenser and being bridged at the ends of said inductances re-,- mote from said tube by a second condenser, each of said condensers comprising a pair of parallel plates carried by resilient arms and means to flex one of said arms of each condenser to vary the capacity thereof.

4. In a radio circuit for ultra high frequencies, a vacuum tube having a grid, plate and cathode, a grid circuit connected to said grid and said cathode, a plate circuit connected to said plate and said cathode, and a tuning circuit for said ultra high frequencies comprising a series inductance in said grid circuit adjacent said tube, a series inductance in said plate circuit adjacent said tube, said grid and plate circuits being bridged adjacent said tube by a condenser and being bridged at the ends of said inductances remote from said tube by a second condenser, and

radio frequency chokes in series in said grid'and plate circuits adjacentlsaid second condenser to confine ultra high frequency currents to said tuning circuit,

5. In a radio circuit for ultra high frequencies,

modulated at a lower frequency,'a vacuum tube having a grid, plate and cathode, a grid circuit connected to said grid and said cathode, a plate circuit connected to said plate and said cathode, and a tuning circuit for said ultra high frequencies comprising a series inductancein said grid circuit adjacent said tube and a series inductancev in said plate circuit adjacent said tube, said grid and plate circuits being bridged adjacent said tube by a condenser and being bridged at the ends of said inductances remote from said tube'by a secnd condenser, said grid and plate circuits being inductively coupled at said lower frequency.

6."In a radio for ultra high frequencies, a vac-,

uum tube having a grid,fplate and. cathode, a

grid circuit connected to said grid and said cathe ode, a plate circuit connected to said plate; and

cathode, a tuning circuit for said ultra high fre quencies comprising a series inductancein said grid circuit adjacent said tube and a series ,in-

ductance in said plate circuit adjacent said tube,

said grid and'plate circuits being'bridge'd adjacent said tube by a condenser and being bridged at the ends of said inductances remote from said tube by a second condenser, said grid and plate 2 circuits being provided with series inductances having mutual inductance and radidfrequency chokes connected between said tuning circuit and said last named inductances.

7; In a radio for ultra high frequencies, modulated at a lower frequency, a vacuum ,tube'having a grid, plate and cathode, a grid circuit connected to said grid and said cathode, a plate circuit connected to said plate and said cathode, and atuning circuit for said ultra high frequencies comprising a series inductance in said grid: circuit adjacent said tube and a series inductance in said plate circuit adjacent said tube, said grid and plate circuits being bridged adjacent said tube by a condenser and being bridged at the ends of said inductances remote from said tube by a second condenser said grid and plate circuits beinginductively coupled at said lower frequency,

said grid circuit having a gridleakbridged by a condenser between saidradio frequency choke and the last named inductance therein.

' JOHN G. S'IREIFFERT.

WILLARD F. BARTOE. 

